Thermostatic switch



Patented Oct. 18,1932

j UNITED STATES PATENT OFFICE JOEN A. SPENCER, OE NEWTON, MASSACHUSETTS, ASSIGNOR TO THE SIPENCER THER- IOSTAT COMPANY, OF CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF MASSA- cnusnrtrs Application filed June 17,

The present invention relates to gas burners especially of the type wherein the supply of fuel to the burner may be controlled by a valve operated by an electrical circuit.

Among the several objects of the invention me. be noted the provision of a thermostaticali y controlled arrangement associated wlth a burner and electrically connected to a valve to stop the flow of fuel to the burner when the burner is not lighted, although it 1s also evident that external heat may be employed in the operation of the device hereinafter described. Other objects will be in part obvious and in part pointed out hereinafter.

A convenient adaptation of the burner 1s to use the body of the burner as a means for controlling the closing and breaking of an electrical circuit to the valve, through the operation of a normally convexo-concave spring metal diaphragm or disc, arranged to snap over dead center thereby transmittmg motion to the member which closes and breaks the circuit through-the valve. The body of the burner forms a temperature actuated member for operating the disc to cause it to snap, the body of the burner and disc being an adaptation of the device described and claimed in my United States Patent 1,678,407, dated July 24, 1928, and the device herein described, represents a decided advance 1n the art through its high degree of simplicity in its construction and its compact form.

The invention accordingly comprises the elements and combinations of, elements, features .of construction, and arrangements of parts which will be exemplified in the structure hereinafter described, and the scope of the application of which will be indicated in the fol owing claims.

In the accompanying drawing, in which is illustrated one of various possible embodiments of the invention,"

1 is an anal section of a burner and F1 switci electrically connected with a motor,

valve; 7 v In the drawing, the body of a gas burner is made up of the tubular member 10 having a burner head 11 secured thereto, the head 11 having'ports 12 therethrough for the passage of gas to be burned. Secured to the head at THERMOSTATIC' SWITCH 1930. Serial No. 461,802.

13 is the rod 14 of substantially greater length than the tube 10, the said rod extending through the tube. The tube 10 is made of metal having a relatively high coefficient of thermal expansion, such as brass or nickel steel, the rod 14 having a lower coeflicient of thermal expansion, such as invar, the c0effi-' cient of thermal expansion of which is prac t1cally zero. Heat from the burner head is conducted to thetube 10, which expands, and

inasmuch as the rod 14 is connected to the tube 10 through the burner head 11, it will move with the expansion of the tube 10.

Although it is clear that the burner may be assembled in many ways, the drawing shows a T-connection15 secured to the end of the tube 10, the rod 14 passing through the joint andfint-o a housing 16 containing the disc and contact members, the housing being secured to the connection 15 Gas flows to the burner head from the line 17 and through the tube 10.

. Within the housing 16 is secured the ring rod 14 engages,provided with lugs 22 which form a continuous member bearing against the diaphragm 2.0, the lugs 22 opposing the lugs 19, so that upon movement of the rod 14 against the plunger 21, there will be applied to the elastic diaphragm 20 oppositely directed forces at spaced intervals to. apply flexing forces to the diaphragm so that the diaphragm will change shape abruptly in response to temperature changes at the burner head.

Secured to the'diaphragm and insulated therefrom by .means of the bushing 29!, is

a contact member 23 adapted to bridge the contacts 24. and 25 when the diaphragm snaps to its normal position due to release of the flexing forces. When this bridging of the contacts occurs,/ current can flow through the circuit including the conductors 26 and 27. If desired, the housing may be grounded, as indicated at 28.

The disc 20 assumes its normal and hot position when the pressure of the rod 14 on the plunger 21 is substantially lessened and in this position (the opposite of that, shown in the figure) it closes the contacts 24 and 25. However, pressure of the rod 14 on the plunger, caused by contraction of the tube 10, snaps the disc to its cold position (Fig. 1)

thereby breaking the circuit.

As long as the burner'is lighted, the circuit through the conductors 26 and 27 is closed by the seating of contact 23 across them thereby keeping a fluid supply valve:

33 open. The fluid supply valve 33 comprises a known type of motor valve which is controlled by the circuit of the conductors 26 and 27. If the burner is extinguished, the tube 10 contracts through cooling and .thus pushes the rod 14 down slightly and increases its pressure on the plunger 21, and causes the diaphragm 20 to snap back into its cold position, shown in the drawing, to break the contact; with the conductors 26 and 27 allowing the supply valve 33 to close to stop the flow of gas. o

Inasmuch as the contact 23 is insulated from the diaphragm 20, no current will flow through the diaphragm, and arcing as the contact is made and broken is reduced to a minimum through the snap action of the diaphragm.

It is desirable to have lugs 19 of the ring 18 between the lugs 22 of the plunger 21 and the rod 14. This arrangement permits the pressure of the rod to be exerted upon the diaphragm near the periphery thereof, the peripheral edge being free, and thus adapted to change shape abruptly in response to flexing forces applied thereto, the burner serving as thermostatic means arranged to apply oppositely directed forces to the diaphragm at spaced points to flex the diaphragm abruptly in response to temperature changes.

It is to be understood that this invention is applicable to burners other than gas burners and also that the heat, producing the movement of rod 14 may be generated by means other than the burner itself.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without department from the scope of theinvention, it is intended that all matter contained in the above description or shown in the accomthe linear expansions of said rod and tube.

2. A burner comprising a tube, a distributing head at one end of said tube and a housing at the other end thereof, a 4 rod in said tube, means in said housing operable to control a circuit, avalve operable to control the supply of fluid to said burner, said valve being controlled by said circuit and said means being actuated at critical temperatures by the diflerent degrees of linear expansion of said rod and tube.

3. A burner comprising a tube, a distributing head at one end of said tube and a housing at' the other end thereof, a rod in said tube, means in said housing 0 erable to control a circuit, a valve opera le to controlthe supply of fluid to said burner, said valve being controlled by said circuit and said means being actuated by'the differences of the linear expansions of said rod and tube, said means comprising a snap-acting disc,

mounted between oppositely disposed and un aligned concentric edges, one of said edges being movable under the pressure of said rod, whereby said disc may be flexed to either of its alternative positions by change of pressure of the rod on the edge.

4. A burner comprising a tube, a distribut- I ing head at one end of said tube and a housing at the other end thereof, a rod in said tube, means in said housing operable to control a circuit, and said means being actuated bythe differences in the linear expansions of said rod and tube, said means comprising a snap-acting disc, oppositely disposed su ports for the disc disposed at different radii with respect to the disc, said disc being mounted between said oppositely disposed supports, one of said supports bein movable under the pressure of said rod, w ereby said disc may be flexed to either of its alternative positions by change of pressure of the rod on the supports.

5. A burner comprising a tube, a distributing head at one end of said tube and a housing at the other end thereof, a rod in said tube, means in said housing operable to con- 1 A burner com rising atube, a distributing head at one en of said tube and ahbus- -in at the other end thereof, a rod in said tu e, means in said housing operable to control a circuit, said means com rising a snapating disc, a switoh operate by said disc, said discswbeing mounted near its outer edgebetween oppos tely disposed concentric abutments, the relative position between said abutments being adapted to be changed by the diflerences 1n the linear expansions of\' said rod and tube, whereby said-diaphragm is flexed to its alternative positions. I In testimony whereof, I have signed my name -tcthis specification this 12th day of June, .1930: JOHN "A. SPENCER. 

